We can save a lot of animals simply by not running over them.

By Joe Crowley


A few summers ago, I was driving to North Bay when I noticed a painted turtle up ahead crossing the road. I quickly pulled over and ran back to help hasten its progress. But before I could save the turtle, another car sped by, crushing the animal.

Roads are a serious threat to Ontario’s wildlife, especially endangered species. Canada has the highest road density per capita in the world, and southern Ontario has among the highest road density in Canada. Southern Ontario’s network of major roads has increased dramatically, from 7,133 kilometres in 1935 to 35,637 kilometres in 1995. It is now so extensive that no point in southern Ontario is more than one or two kilometres from the nearest road. Needless to say, roads have become a dominant threat to southern Ontario’s biodiversity.

Road mortality is bad news not simply because animals are being killed, but because the mortality rate is often high enough to eliminate entire populations. Ontario’s turtles are particularly vulnerable. Turtles have long lifespans (over 70 years in some species) and slow rates of reproduction. Consequently, the deaths of even a few turtles a year will cause populations to decline. Roads have contributed to the sharp drop in Ontario’s turtle species – seven of the province’s eight turtle species are now so diminished in number that they are classified as at risk.

The impact of a roadway on the landscape, however, extends beyond the area of the road corridor itself. For instance, some songbirds cannot use habitat located within a kilometre of busy roads, because the traffic noise prevents them from communicating. A study in the United States found that, although roads cover only about 1 percent of the land, they affect as much as 20 percent of it. Roads also act as barriers to movement, either because animals avoid roads or cannot cross them. In doing so, roads subdivide and isolate populations in smaller and smaller patches of habitat.

Even provincial and national parks are criss-crossed by roads. Indeed, Algonquin Provincial Park has more kilometres of road than the City of Toronto. A recent study in Ontario found that rates of road mortality in a national and provincial park were as high as road mortality rates outside the parks. Ironically, the roads we drive on to get to parks to appreciate nature are probably the primary threat to wildlife populations in those areas.

But the most detrimental impact of roads on the natural environment is that they provide access to previously undisturbed areas. By providing access to natural resources, roads create opportunities for illegal collection and poaching, point-source pollution, the spread of invasive species and other forms of environmental degradation.

Obviously, the most effective way to reduce road mortality is simply not to build roads – an unlikely scenario. Worse, when road projects are undertaken, species at risk are often overlooked during the environmental assessment process. When endangered or threatened species are detected, their protection rarely trumps construction. Ontario’s Provincial Policy Statement safeguards wildlife habitat from development, yet it does not consider road construction. Even the new Ontario Endangered Species Act fails to offer effective protection from roads, since permits can be issued to projects that will destroy habitat if those projects provide a significant social or economic benefit. For example, a permit is being issued to the Detroit River International Crossing project even though its construction will damage the habitat of eight species at risk.

Other solutions to lessen the impacts of roads on wildlife populations include wildlife overpasses and underpasses for large mammals, specially designed culverts for small animals, wildlife fencing and animal-crossing signs. The most effective mitigation measures, however, are the most expensive and are rarely used. Ontario has yet to construct a single large-wildlife underpass or overpass.

To address the threat roads pose to the natural environment, scientists, policy makers, biologists, government representatives and engineers have come together to form the Ontario Road Ecology Group. Answers will require a shift in our thinking about roads, must be multidisciplinary, involve multiple stakeholders, and range in scope from local solutions to invoking provincial policy. We need to acknowledge that mitigating the impacts of roads on Ontario’s wildlife and wilderness areas is essential to preserving this province’s biodiversity.

Joe Crowley is Ontario Nature’s reptile and amphibian atlas coordinator.